Participation in regular physical activity (PA) reduces the risk of cardiovascular disease, diabetes, obesity, and certain forms of cancer.[1-3] Despite the numerous benefits of PA, only a minority of American adults engage in regular PA,[4,5] and most who begin an exercise program do not continue.[6-8] Indeed, Physical inactivity has been called the most significant threat to American public health for the 21st century.[16] There is a great need to develop innovative approaches to promoting increased PA that are engaging in a way that helps sustain continued practice. Videogames that require physical activity for play (also called "Exercise Videogames" or "EVGs") have been widely marketed to millions of U.S. households and are played by both children and adults.[9] Emerging research indicates that a single session of these games can produce significant increases in metabolic expenditure and increase heart rate to levels equaling moderate-to-vigorous physical activity[10,11] that may translate into health-related fitness improvements.[12,13] However, to date there is insufficient research to determine whether adults will engage in regular EVG participation sufficient to produce improvements in cardiovascular fitness and overall health risk. In addition, EVGs may also tap into certain cognitive and affective constructs to a greater degree than standard PA programs, encouraging greater participation and maintenance of PA.[60-61] The proposed trial builds on our highly successful pilot study, in which adults given a 12-week program of EVGs showed improvements in fitness and measures of cardiovascular fitness (including step test duration, balance, resting heart rate, blood pressure, etc.). For the proposed study we will conduct a 3-group randomized, controlled trial among healthy, sedentary adults (age >or =18), to test the efficacy of EVGs compared to a standard exercise program (Standard) and contact-control (Control) to increase time spent in PA and changes in physical fitness and cardiovascular health. We will also examine maintenance of PA and fitness changes during a 6-month home based EVG and Standard interventions (Months 4-9). This study will also examine changes in theoretically-based constructs that will shed light on the cognitive and behavioral mechanisms underlying observed between-group differences in adherence to PA. The proposed study will advance the field by: (1) establishing the efficacy of EVGs for increasing participation in PA;(2) demonstrating the efficacy of EVGs for PA maintenance when used in the home;(3) Demonstrating the potential of EVGs for improving cardiovascular health and overall fitness;and (4) testing theoretical constructs that may contribute to greater adherence, and ultimately, efficacy of EVGs compared to standard forms of PA. PUBLIC HEALTH RELEVANCE: This study will test a rigorous, randomized controlled clinical trial comparing exercise videogames and a traditional exercise program for increasing physical activity participation and maintenance of physical activity among adults. Exercise videogames may invoke unique social and psychological factors that attract those who are not engaged in traditional exercise programs. Finding novel, effective methods to engage adults in regular physical activity has the potential to reduce their risk of developing numerous diseases such as cardiovascular disease and certain types of cancer.